<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>主窗口</title>
    <style>
      iframe {
        height: 100px;
        width: 200px;
      }
    </style>
  </head>
  <body>
    <iframe id="ifr" src="./index.html"></iframe>

    <script>
      var frame = window.frames[0];
      //   var isInstanceOf = [] instanceof frame.Array;
      var isInstanceOf = [] instanceof Array;
      console.log("frame.Array", frame.Array);
      console.log("isInstanceOf", isInstanceOf);
    </script>
  </body>
</html>
